Apparatus for depositing metal by electrode dispersion



June 9, H w WHISTON ET AL I APPARATUS FOR DEPOSITING METAL BY ELECTRODE DISPERSION Filed Dec. 16, 1935 Z'Sheets-Sheet 1 /NVE'/VTORS, flare/a WWfirIsfon,

June 9, 1936.

H. W. WHISTON El AL APPARATUS FOR DEPOSITING METAL BY ELECTRODE DISPERSION Filed Dec. 16, 1935 2 Sheets-Sheet 2 9 F lg. 2.

U l a O I I 0 r1 0 George 415. IM /vol: Frz'gdricfi 111M T/rejm Patented June 9, 1936 UNITED STATES PATENT OFFICE APPARATUS FOR DEPOSITING METAL BY ELECTRODE DISPERSION of Great Britain Application December 16, 1935, Serial No. 54,760 In Great Britain April 21. 1934 8 Claims. (Cl. 91-123) This invention relates to the deposition of metal by cathode dispersion. It is -particularly concerned with the deposition of precious metals such as gold, silver and platinum, and the object of the invention is to provide a process for depositing the metals by cathode dispersion direct on textile threads, that is to say, to produce metallized threads suitable for use for weaving, knitting, embroidery, sewing or other textile purposes and in particular gold or silver covered threads which may be used for the braiding of uniforms and for other purposes.

Proposals have previously been made to coat threads with metal by cathode dispersion within a vacuum chamber but these proposals involved either the continuous passing of the threads through the vacuum chamber with consequent practical difiiculties in maintaining the vacuum in the chamber during operation or carrying the thread to be coated on bobbins and winding the coated threads on further bobbins mounted within the vacuum chamber and driven by a motor arranged externally of the vacuum chamber.

According to the present invention, in a method of coating a length of thread with metal by means of cathode dispersion, the thread is supported during the process upon a framework mounted within a vacuum chamber which contains electrodes arranged within and externally of the framework. The framework may be in the form of a rotatable swift upon which the thread to be coated is wound with sufficient spacing between the individual turns of the thread to ensure that substantially the whole of the surface of the thread is exposed to the metal particles dispersed from the electrodes. The swift may be removable as a complete unit from the vacuum chamber in order to facilitate winding the thread upon it before treatment and remov- 4O ing the thread after treatment, and the vacuum chamber itself may be exhausted of air continually during the coating treatment, the electrodes being maintained cool by a cooling medium.

In order that the nature of the invention may be more clearly understood and readily carried into effect, a piece of apparatus for carrying out the method according to the invention will now be described by way of example with reference to the accompanying drawings, in which:-

Figure 1 is an elevation in section of a vacuum chamber containing electrodes and a swift upon which the thread to be coated will be wound;

Figure 2 is a part plan view of Figure 1 showing more clearly the relative disposition of the electrodes and the swift;

Figure-3 is an enlarged view of the swift showing the construction in greater detail, and

Figure 4 is a fragmentary view showing the cross-section of one rib of those used to support the thread on the swift. 5

Referring to Figure 1 of the drawings, a vacuum chamber 1 of cast iron is provided with an annular shoulder 2 designed to support the chamber upon a stand not shown in the drawings. The wall of the chamber I has a port 3 at which 10 a vacuum pump is connected in order that the chamber may be maintained exhausted of air during the coating treatment. The open end of the chamber I is closed by a cover plate not shown in the drawings, but which, during the 15 coating process, is tightly seated in position in an annular recess 4, and the cover plate is re-, movable to allow the swift 5 to be placed within and withdrawn from the chamber I. The construction of the swift 5 will be described in great- 20 er detail later but it may here be noted that it is provided with a handle 6 to facilitate its being placed within and withdrawn from the chamber l.

Conductors I pass through insulating bush- 25 ings B to electrodes 9 arranged to form three arcs of a circle, two of which are shown partially in Figure 2 of the drawings. A further conductor I0 enters the bottom of the chamber I through an insulating bushing H and is con- 30 nected to a semi-circular electrode l2. In Figure 2 of the drawings'a second semi-circular electrode I3 is shown with the electrode I2 varranged within the swift 5. The conductors l and I0 and also the arc and semi-circular shaped 35 members of the electrodes are hollow to permit the passage of cooling water through them. The upper and lower members of the electrodes are connected by vertical tubes 9a, I2a, so that the whole of each electrode is maintained cool.

' The swift 5 is supported upon a spindle H by curved arms I 5 which extend radially inwards and downwards from the periphery of the swift. The arms l5 unite to form a hub IS in which a 45 slot I1 is formed and a pin l8 projecting from the spindle l4 into the slot ll provides a driving connection between the spindle and the swift. The spindle I4 is mounted in bearings I9 in a bracket 20 extending below the chamber I and 50 receives further support in bearings 2| in abracket 22 within the chamber I.

The adoption of the curved arms [5 for supporting the swift 5 upon the spindle l4 ensures that the swift may be rotated without fouling 55' the electrodes l2 and I3 arranged within the swift.

In order to ensure that a vacuum may be maintained within the chamber 1 during the coating process, a mercury-sealed gland 23, 24, 25 is provided at the point where the spindle it passes through the bottom of the chamber l.

The construction of the swift 5 itself is shown more clearly in Figures 3 and 4 of the drawings, particularly in regard to the ribs 26 connecting the upper and lower end. rings which may be of aluminium or stainless steel. The ribs 26 are notched in order to provide spacing teeth for the individual turns of the thread 21 wound upon the swift. A cross-section of a single rib 26 taken on the line IVIV in Figure 3 is shown in Figure 4 in which the thread 21 is shown in contact with the notched edge of the rib. The rib 26 is shown mounted within a slot 29 formed in the end ring of the swift 5. The end of each rib is formed with an extended screw-threaded portion 30 which is e aged by a conical nut 3| to secure the rib in position. The end rings of the swift 5 are formed with reinforcing projections 32 having recesses which receive the nuts 3|. The area 'of actual contact between the thread and the edges of the individual ribs is made as small as possible in order to ensure that no substantial portions of the thread will be uncoated. In carrying out the method according to the invention, the thread to be coated is first wound upon the swift 5 which is then placed within the chamber I. When sealed, the chamber is exhausted by air by means of vacuum pumps which continue operating during the coating treatment in order to maintain the vacuum. Alternating current is applied to the electrodes 9, I2 and I 3, the surfaces of which are of the metal with which it is desired to coat the thread. This may, for example, be gold, silver or platinum. In order that the electrodes may be maintained cool, water from tank 35 is caused to circulate through them. The spindle I4 is driven by a motor of convenient form, not shown in the drawings, and the actual speed of rotation may be about 10 or 20 revolutions per minute. It is only necessary to provide sufficient movement of the swift which will ensure even deposition of the particles of metal. At the end of the coating treatment the current is switched off, the drive to the spindle I4, vacuum pump and water circulating means is stopped, and the swift is removed from the chamber. The coated thread is then wound onto spools or bobbins. In order to ensure that the whole surface of the thread is completely coated, it may be rotated by winding again onto the swift, care being taken that those portions of the thread which in the first treatment rested upon the ribs 26 are freely exposed. An alternative method of ensuring complete coating is to provide the swift with auxiliary ribs between the ribs 26 and not in the first instance in contact with the thread but to which the thread may be transferred for the second treatment.

After the coating process is completed, the thread may be further treated with various solutions or covered with fine films which protect the metal on the thread from being touched or affected by the human hand or atmosphere inside or outside the room in which the operation takes place or in subsequent use. The finished thread can also be twisted to form multiple thread if required. Again, it can be used for the covering of an inner core used for various purposes and in various trades and consisting of material such as hemp, fine rubber latex, and so forth.

It will be understood that modifications in addition to those already indicated may be made within the scope of the invention. Thus, for example, the construction of the electrodes themselves may be modified by providing instead of the tubes 9a, l2a. thin solid rods or wires suspended from the upper arcs or semi-circular shaped ends forming the electrodes. The process 10 may be worked with either alternating or direct current. When alternating current is employed, the arc-shaped electrodes 9 are connected by the conductors I through their bushings 8 to one pole, and the inner arc-shaped electrodes [2 and l5 l3 are connected by conductors I0 through bushings H to the other pole. When direct current is employed, the are or semi-circular shaped electrodes are all connected to the negative terminal of the source of supply and an additional knob- 20 shaped electrode 28, projecting through the bottom of the vacuum chamber at the point indicated in Figure 2, is connected to the positive terminal to form a single anode. This anode, which may also be water-cooled, is short, and adequate clear- 25 ance is provided between it and the bottom tube l2 of the inner semi-circular electrode above it.

It will be understood that any threads used in the textile industries may be coated by the method described. Such threads may, for example, be 30 of regenerated cellulose, cellulose acetate or other artificial silk, and so forth.

We claim:

1. An apparatus for coating a length of thread with metal by cathodic dispersion comprising 35 a vacuum chamber, a support mounted within said chamber and shaped to carry the thread fixedly disposed thereupon and to contact therewith only at relatively widely spaced small areas thereof, and a plurality of electrodes mounted 40 within said chamber comprising a plurality of cathodes'mounted on opposite sides of the thread.

2. An apparatus for coating a length of thread with metal by cathodic dispersion comprising a vacuum chamber, a support mounted within said chamber formed as a closed frame adapted to carry the thread fixedly disposed thereupon and to contact therewith only at relatively widely spaced small areas thereof, and a plurality of electrodes mounted within said chamber comprising at least one cathode upon both the inside and outside of said frame.

3. An apparatus for coating a length of thread with metal by cathodic dispersion comprising a vacuum chamber, a support mounted within said chamber formed as a closed frame by two circular end rings with longitudinal rods extending therebetween adapted to carry the thread fixedly disposed thereupon and to contact therewith at spaced points along said rods, and a plurality of electrodes mounted within said chamber comprising arc-shaped cathodes concentric to the circular end rings upon both the inside and outside of said frame.

4. An apparatus for coating a length of thread with metal by cathodic dispersion comprising a vacuum chamber, a shaft extending through a wall of said chamber into the interior thereof, a frame mounted detachably on said shaft and adapted to be inserted and withdrawn from said vacuum chamber as a unit, said frame adapted to have the thread fixedly mounted thereon and said thread adapted to make contact with said frame only at relatively widely spaced small areas of said thread. and a plurality of elec- 7E trodes mounted within said chamber comprising a plurality of cathodes disposed on the interior and exterior of said frame on opposite sides of the thread.

5. An apparatus for coating a length of thread with metal by cathodic dispersion comprising a vacuum chamber, a support mounted within said chamber and shaped to carry the thread fixedly disposed thereupon and to contact therewith only at relatively widely spaced small areas thereof, and a plurality of electrodes mounted within said chamber comprising a plurality of cathodes mounted on opposite sides of the thread, said cathodes being hollow at least in part whereby to permit a cooling medium to be passed therethrough.

6. An apparatus for coating a length of thread with metal by cathodic dispersion comprising a vacuum chamber, a shaft mounted for rotation extending through a wall of said chamber into the interior thereof, a frame in the form of a surface of revolution mounted detachably on said shaft and adapted to be inserted and withdrawn from said vacuum chamber as a unit, said frame adapted to have the thread fixedly mounted thereon and said thread adapted to make contact with said frame only at relatively widely spaced small areas of said thread, and a plurality of electrodes mounted within said chamber comprising a plurality of cathodes disposed on the interior and exterior of said frame on opposite sides of the thread.

7. An apparatus for coating a length of thread by cathodic dispersion comprising a vacuum chamber, a support mounted within said chamber formed as a closed frame having two end members and a plurality of notched longitudinal rods extending therebetween whereby to fixedly support the thread at widely spaced small points thereof, and a plurality of electrodes mounted within said chamber comprising cathodes mounted interiorly and exteriorly of the frame on opposite sides of the thread.

8. An apparatus for coating a length of thread with metal by cathodic dispersion comprising a vacuum chamber, a shaft mounted for rotation extending through a wall of said chamber into the interior thereof, a frame in the form of a surface of revolution mounted detachably on said shaft and adapted to be inserted and withdrawn from said vacuum chamber as a unit, said frame adapted to have the thread fixedly mounted thereon and said thread adapted to make contact with said frame only at relatively widely spaced small areas of said thread, and a plurality of electrodes 'mounted within said chamber comprising a plurality of cathodes disposed on the interior and exterior of said frame on opposite sides of the thread. said cathodes being substantially concentric to and of a length substantially coincident with the surface of revolution of said frame.

HAROLD WALTER WHISTON. GEORGE ARTHUR BALFOUR MCIVOR. FRIEDRICH WILHELM NIKOLAUS THEIN. 

